Aguilarite

Formula:  Ag₄SeS

_{Strunz number:  2.BA.5}

Origin of name:  for S.Aguilar, Mexican mine superintendent of the San Carlos mine, Guanajuato, where the mineral was originally found

Crystal system:  Orthorhombic

Crystal class:  Unknown

Twinning:

Unit cell:  a = 4.33 Å, b = 7.09 Å, c = 7.76 Å

Colour:  Lead-gray, iron-gray to iron-black, dull on exposed surfaces

Diaphaneity: Opaque

Luster:  Metallic, brilliant

Habit:  Poorly formed dodecahedral crystals with pitted surfaces and rounded edges; massive

Hardness:  2.5

Specific gravity:  7.40 to 7.59

Cleavage:  None

Tenacity: Sectile

Streak: Grayish black

Synonyms/varieties: none

Comments:  Relatively low temperature mineral in hydrothermal deposits rich in silver and selenium, but deficient in sulfur